Complications Drive Post-MI Readmissions

Action Points

Rehospitalization rates have attracted major attention and have become a marker of quality of care.

Point out that this study suggests that comorbid conditions, longer length of stay, and complications of angiography and revascularization or reperfusion are associated with increased 30-day rehospitalization risk after MI, and, in fact, many rehospitalizations seem to be unrelated to the incident MI.

A return to the hospital soon after an admission for myocardial infarction (MI) often relates more to complications and comorbidities than to the heart attack itself, researchers found.

Over 30% of rehospitalizations within 30 days of an MI were deemed unrelated to the incident event, according to an observational study by Véronique L. Roger, MD, MPH, of the Mayo Clinic in Rochester, Minn., and colleagues.

Comorbidities and complications of treatment weighed heavily among the risk factors for readmission, the group reported in the July 3 issue of the Annals of Internal Medicine.

The rate of repeat admission reached 35.3% among patients with an angiography complication during their initial stay and 31.6% among those with a reperfusion or revascularization complication.

That was nearly double the 16.8% rate of 30-day readmission among patients who were reperfused or revascularized without complications.

"Prevention of complications and close follow-up for patients who have had a complication may be of particular importance for preventing rehospitalizations," Roger's group noted.

Another implication is for coordination of care, as comorbidities are so common in MI patients.

With an aging population and 30-day rehospitalization now used as a quality of care marker, "these data underscore the importance of implementing a comprehensive management strategy in patients after incident MI to help prevent rehospitalizations," the researchers wrote.

Their study included 3,010 incident MIs from 1987 to 2010 within the population-based registry of Olmsted County, Minn., where the Mayo Clinic is located.

Among these cases, 42.6% were rehospitalized related to the incident MI or its treatment, for reasons such as sternal wound infection, heart failure, acute renal failure, or pleural effusion.

The 30.2% deemed unrelated to the initial MI were for reasons such as cancer, fracture, aspiration pneumonia, and end-stage renal disease in patients on dialysis prior to MI.

The remaining 27.2% of rehospitalizations didn't clearly fit into either category and were most commonly for atypical chest pain.

Significant, independent risk factors for readmission within 30 days of the initial MI were:

A complication of angiography during the index hospitalization (hazard ratio 2.40)

A complication of reperfusion or revascularization during the index hospitalization (HR 2.12)

Diabetes mellitus (HR 1.34)

Chronic obstructive pulmonary disease (HR 1.43)

Anemia (HR 1.25)

Worse heart failure as marked by a higher Killip class at presentation (HR 1.22 for class 2 to 4)

A longer initial hospitalization (HR 1.34 for 4 to 7 days and 1.65 for more than 7 days compared with 3 or less)

Acute kidney injury after percutaneous coronary intervention during the index MI hospitalization, which occurred in 5% of patients, boosted risk of readmission 92% after adjustment for baseline kidney problems. But it wasn't often a primary reason for rehospitalization.

Rehospitalization after MI showed no trends over time during the 24-year study period.

"Despite advances in therapies and improved inhospital outcomes after MI, rehospitalizations remain a serious problem and have shown no signs of abating," Roger's group concluded.

Limitations of the study included that missed MIs that did not result in hospitalizations, and hospitalizations that occurred outside of the county studied as well.

The largely white population of the county might have limited generalizability too.

The study was funded by grants from the National Institutes of Health and the Rochester Epidemiology Project.

Roger reported grant funds to her institution from the National Heart, Lung and Blood Institute.

Reviewed by Zalman S. Agus, MD Emeritus Professor, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner

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